Generally, a battery pack is a kind of power supply that is charged with power (electric energy) received from an external charger and supplies the power so that portable electronic devices, such as cellular phones, personal digital assistants (PDAs) and the like can be operated, and consists of a battery cell which is charged with electric energy and circuits for charging and discharging the battery cell (supplying electric energy to portable terminals).
The electrical connection between the battery pack, which is used in the portable terminals, and the charger for charging electric energy to the battery pack may be achieved using a connector supply system, which receives the power from a regular power source and converts the voltage and current thereof to correspond to those of the battery pack, and supplies the electric power to the battery pack via a connector of the corresponding battery pack.
However, such a connector supply system has drawbacks, including. instant discharge owing to the difference in potential between the charger connector and the battery connector, the risk of fire and concomitant damage due to fire caused by the presence of foreign substances, reduction in the life and performance of the battery pack, and the like.
To solve the above-mentioned problems, a non-contact charging system and control method thereof using a wireless power transmission system were recently proposed.
This non-contact charging system includes a non-contact power transmission apparatus for wirelessly supplying electric power, a non-contact power receiving apparatus receiving the electric power from the non-contact power transmission apparatus and charging the battery cell with it, and the like.
Meanwhile, due to its non-contact nature, the non-contact charging system conducts a charging- operation while the non-contact power receiving apparatus is placed in the non-contact power transmission apparatus.
Here, if foreign substances, such as a metal, are placed in the non-contact power receiving apparatus, the foreign substances cause problems such as abnormal power transmission, product damage due to fire caused by overload or the like.
The information disclosed in this Background of the Invention section is only for the enhancement of understanding of the background of the invention and should not be taken as an acknowledgment or any form of suggestion that this information forms the prior art that would already be known to a person skilled in the art.